Assign a File Password

1. Open a workbook or select an already opened workbook you want to protect.
2. Click the Office button and choose Save As. Excel displays the Save As dialog box.
3. Click Tools and choose General Options from the menu. Excel displays the General Options dialog box.
   
   
   
   
   
   
4. In the Password to Open text box, enter a password that must be used before a user can open the workbook.
5. In the Password to Modify text box, enter a password that must be used before a user can save the workbook under the same filename. Passwords can be up to 15 characters and are case sensitive.
6. Click OK. Excel asks you to reenter the passwords for confirmation.
7. Reenter the passwords.
8. Windows XP: In the Save In drop-down, select the folder in which to save the workbook and then click Save.
   Windows Vista: If the Folders window is not displayed, click Browse Folders, click Folders to display the Folders window, and then select the folder in which to save the document. Then click Save.
   
9. If you are saving the workbook with the same name, respond when Excel displays a message asking you to confirm overwriting the file.

The General Options dialog box offers other safeguarding options. Select the Always Create a Backup check box if you want Excel to always save a backup copy of the existing workbook before you save the workbook.